充气空心毛细管光纤中孤子动力学实现低至200 nm的超宽带瞬态吸收
Ultra-broadband transient absorption down to 200 nm enabled by soliton dynamics in gas-filled hollow capillary fibers
AI总结：
该研究利用充气空心毛细管光纤的孤子动力学，实现了覆盖200-800 nm的超宽带飞秒瞬态吸收，分辨率达9 μOD，成功解析Fe(II)配合物的DUV超快自旋交叉动力学，为研究DUV波段光物理化学动力学提供了新方法。
AI中文摘要：
深紫外（DUV）窗口（200-300 nm）对于通过核碱基、氨基酸、肽键、多种有机基团及宽带隙跃迁的紫外特征来表征（生物）化学和材料系统至关重要。然而，将超快光谱技术扩展至DUV波段以获取相关电子和结构动力学信息在很大程度上仍难以实现，原因在于常规飞秒DUV脉冲源的带宽和效率有限。我们如今填补了这一空白，展示了覆盖200-800 nm的超宽带飞秒瞬态吸收（TA），实现了对整个DUV窗口前所未有的覆盖。我们通过在氦气填充的空心毛细管光纤中利用孤子自压缩产生超连续谱探测脉冲，重复频率为20 kHz，并通过相关矩阵参考方案完全抑制其固有的高强度波动。因此，我们实现了探测器噪声极限下的TA测量，在1秒内达到了9 μOD的卓越分辨率，并通过解析Fe(II)配合物在DUV中的超快自旋交叉动力学，展示了这些新能力。这项工作为揭示编码在DUV中此前无法获取的光物理和光化学动力学开辟了道路。
英文摘要：
The deep ultraviolet (DUV) window (200-300 nm) is essential for the characterization of (bio)chemical and material systems through the UV signatures of nucleobases, amino acids, peptide bonds, many organic moieties, and wide bandgap transitions. However, extending ultrafast spectroscopy to the DUV to access the associated electronic and structural dynamics has largely remained elusive, due to the limited bandwidth and efficiency of common femtosecond DUV pulse sources. We now close this gap and demonstrate ultra-broadband femtosecond transient absorption (TA) spanning 200-800 nm, achieving unprecedented coverage of the entire DUV window. We generate supercontinuum probe pulses through soliton self-compression in a helium-filled hollow capillary fiber at a repetition rate of 20 kHz and fully suppress their high intrinsic intensity fluctuations via a correlation matrix referencing scheme. We thus achieve detector-noise-limited TA measurements with an exceptional resolution of 9 $μ$OD in one second, and demonstrate these novel capabilities by resolving the ultrafast spin-crossover dynamics of a Fe(II) complex in the DUV. This work opens the path to unravel previously inaccessible photophysical and photochemical dynamics encoded in the DUV.
